I propose to apply ultrastructural techniques to the histological study of the human organ of Corti and the histopathology of human deafness. Light microscopic studies of the pathological human inner ear has demonstrated that loss of sensory and neuronal cells and alterations in the stria vascularis and perhaps in supporting structures are the histological correlates of most forms of human deafness. The resolution offered by electron microscopy, which has provided new information concerning the structure of the mammalian organ of Corti, can be applied successfully to the study of human material, normal and pathological, for which animal models are not available or representative. A method is outlined to overcome previous difficulties with ultrastructural evaluation of the human organ of Corti, including procurement of temporal bones with sufficient premortem otological and audiological data and also the initiation of fixation within sufficiently little time after death to allow preservation adequate to permit an ultrastructural analysis.